I just sent out an email to my customers, galleries, artist friends, etc. One of my artist friends wrote back "Your newsletter is also a major inspiration, it's something I must do. Hard to find the time while trying to supply galleries/enter shows."
To me that is like saying, "It's hard to find time to brush my teeth because I am so busy eating". I happen to know that this artist friend has several wonderful paintings in each of her galleries. Filling the walls of the gallery is like over eating. You are more attractive if you eat a balanced diet and don't stuff yourself. People find it easier to buy your work if they are not over whelmed by too many choices.
My suggestion is to Go On a Diet. Instead of sending more and more work to the galleries, spend time creating a newsletter and communicating with the world.
I actually quit sending my monthly newsletters because I was getting little, if any, response. Instead, I send out emails when I have news (accepted into shows, won an award) and when I have a new painting. I try to send something out once a week. This brings in lots of response. I also like to keep images on several website and keep up with my blogs.
And how much time does it take? As little or as much time as I have. If I sit down and do this all at once it can take me 2-3 hours. But I usually breakup the task into small bits. I have my email addresses in different folders: customers, friends, galleries, media. The first people who get my email are my customers. I use Mozilla Thunderbird for my email and am able to personalize the emails, click "Send" and I'm off to the easel while the computer is sending all the emails. Later, I come back and send emails to the rest of my contacts.
If you have time to post on Facebook, you have time to send an email.
My blogs and images on websites are done in a similar fashion. I prepare an image with description and put it on my own blog (sharing the info on Facebook and Twitter) Then over the next few days I put the same info on other website where I show my work. It really take very little time each day.
The trick is to get in the habit of doing it. Yes, sometimes you really DO need to stay in the studio and paint and the blogs and emails get neglected. And that's ok. Just get back on your diet as soon you can and stay in touch with the world.